Boring machine with cutter tooth adjustment

ABSTRACT

A rotary and tubular spindle projects from a reciprocatory tool head and carries a radially expandable and retractible tooth for finish boring the hole in a workpiece. This tooth is fixed to the free end of a cantilever bent radially by the camming action of a thin wedge acting through a pair of roller bearings to adjust the tooth radially to a position determined by a stop on the head disposed beyond the other end of the spindle and engageable with a power actuated push rod extending through the spindle and past the stop. The stop may be adjusted axially in fine increments by a screw and nut actuated by a reversible electric stepping motor which may be activated when adjustment of the finishing tooth is needed to compensate for wear and when the tooth is out of engagement with the workpiece to be bored. The cutting tooth, cantilever and wedge surface assembly may be duplicated and disposed in transaxial planes angularly spaced around the spindle axis. The cantilever may be modified to provide for the boring of holes smaller in diameter than the supporting spindle.

United States Patent 1 3,625,625

[72] Inventors Jan Van Roojen; Primary Examiner-Gerald A. Dost Kenn hboth of R0ckf0rd, Altomeywolfe, Hubbard, Leydig, Voit & Osann, Ltd. [2]]Appl. No. 26,293 [22] Filed Apr. 7, 1970 [4S] Patented Dec. 7, 1971 [73]Assignee The lngersoll Milling Machine Company Rockford, Ill.Continuation-impart of application Ser. No.

ABSTRACT: A rotary and tubular spindle projects from a reciprocatorytool head and carries a radially expandable and retractible tooth forfinish boring the hole in a workpiece. This tooth is fixed to the freeend of a cantilever bent radially by 26 293 the camming action of a thinwedge acting through a pair of roller bearings to adjust the toothradially to a position determined by a stop on the head disposed beyondthe other end of [54] BORING MACHINE WITH CUTTER TOUT the spindle andengageable with a power actuated push rod ex- ADJUSTMENT tending throughthe spindle and past the stop. The stop may be 27 Claims 16 DrawingFigs. adjusted axially in fine increments by a screw and nut actuated bya reversible electric stepping motor which may be activated [52] U.S. Cl408/158 when adjustment of the finishing tooth is needed to compen [51'f CI 1323b 39/00 sate for wear and when the tooth is out of engagementwith the [50] Field of Search 408/ l 53, workpiece to be bored 179 Thecutting tooth, cantilever and wedge surface assembly may be duplicatedand disposed in transaxial planes angularly [56] References Cited spacedaround the spindle axis.

UNITED STATES PATENTS The cantilever may be modified to provide for theboring of 3,5 30,745 3/1967 Milewski 408/158 holes smaller in diameterthan the supporting spindle.

PATENTEDUEB nan $625,625

SHEET 2 0F 6 PATENTEU DEE 7:97: 3.625625 mam my 4/. #064 PATENIEU DEC71971 3625525 sum 5 [IF 6 WWI/V5303 BORING MACHINE WITH CUTTER TOOTHADJUSTMENT CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of our pending application Ser. No. 706,254, filedFeb. 19, 1968 and now abandoned.

BACKGROUND OF THE INVENTION The invention relates to the mounting of acutting tooth on a rotary boring spindle for radial adjustment tocutting position or for wear adjustment and has more particularreference to a cantilever type tooth mounting actuated by a wedgeshiftable along the spindle axis by a selectively operable poweractuator.

Adjustable tooth mountings of this general character are disclosed inPat. Nos. 2,734,402 (77-4), 3,12l,350(77-57), 3,226,IOI(29cyv.,3,36l,Ol3(77-2) and 3,39l,585(77-4).

SUMMARY OF THE INVENTION One objective of the present invention is toprovide an adjustable cantilever mounting of the above character whichsupports the cutter bit with much greater rigidity than has beenpossible heretofore and thus achieves greater accuracy in the formationof the holes bored in the different positions of adjustment of the bit.This objective is achieved in part by mounting an extremely stiffcantilever on and extending the same along the exterior of a tubularboring spindle and bending the cantilever by a wedge of small slopedisposed within the spindle and movable along the axis thereof, thewedge having follower and backup surfaces of sufficiently large area andfriction characteristics to transmit the high pressure needed forbending the stiff cantilever.

Attainment of the foregoing objective is facilitated by transmitting thewedging force through a novel arrangement of antifriction bearingelements and by applying such force through a rod moved along thespindle axis by a power actuator between stops, one of which is adjustedselectively in accurately measured increments by controlling theenergization of a reversible electric step motor.

Another object is to adapt the cantilever mounting for the boring ofsubstantially smaller holes than has been possible heretofore.

Still another object is to correlate the back and forth movements of thewedge actuating rod so as to permit the finish boring tooth to actduring retraction of the boring head and remain inactive as the head isfed forwardly to effect rough boring of a work hole.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical cross-sectionalview through a boring head equipped with cutter tooth adjustingmechanism embodying the novel features of the present invention.

FIGS. 2 and 3 are sections taken respectively along the lines 2-2 and3-3 of FIG 1.

FIG. 4 is a fragmentary perspective view of the boring cutter.

FIG. 5 is an enlargement of the lower part of FIG. 2 with the finishingtooth in expanded position.

FIG. 6 is a fragmentary perspective view of the tooth expanding wedge.

FIG. 7 is a section taken along the line 77 of FIG. 5.

FIG. 8 is an enlargement of the upper part of FIG. 2.

FIG. 9 is a schematic view and diagram of the electric and hydrauliccircuits.

FIG. 10 is a fragmentary side view of a modified form of the cantilevertooth mounting adapted for boring small holes.

FIG. 11 is a section taken on the line 11-11 of FIG. 10.

FIG. I2 is a fragmentary and broken away perspective view of the boringtooth and its mounting.

FIG. 13 is an end view like FIG. 3 but showing the cutter equipped withthree finishing teeth.

FIG. 14 is a schematic perspective view of the wedge and roller bearingsof the cutter shown in FIG. 13.

FIG. 15 is an enlarged cross section similar to FIG. 7 but showing themultiple blade finishing cutter, the section being taken approximatelyalong the line 15-15 of FIG. 14.

FIG. 16 is a fragmentary section taken along the line l6l6 of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention is shown in thedrawings incorporated in a boring machine having a tool head 10reciprocable along ways 11 (FIG. 9) by a suitable actuator which maycomprises a piston 12 disposed within a stationary cylinder 13 andreciprocable through a range a (FIG. 9) that may be deter mined in theusual way by limit switches LSa, LSf, LSr actuated by a cam 146 on thetool head and operating conventional value mechanism shown in FIG. 9 toproduce a desired cycle of rapid approach, forward feed 1, return feed band rapid return motions of the head to the position shown in FIGS. 1and 9. A tool spindle 17 composed of separable parts is journaled in thehead and projects cantilever fashion and parallel to the ways from thelower end of the head. Herein, the spindle is journaled in a sleeve 14through the medium of radial and axial thrust bearings 18, the sleevehaving an end flange 15 clamped to the lower end of the head by screws16 and the bearings 18 axially spaced along the sleeve and held betweena flange l9 and adjusting nuts 20. Above the nuts 20, the spindlecarries a pulley 22 herein driven through a toothed belt 23 from anelectric motor 24 (FIG. 9) carried by the head 10. The motor may alsodrive the parallel spindle 17 of a similar boring unit carried by thehead [0.

Rough or semifinish of a work hole 25 in a workpiece 26 secured in asuitable fixture 27 is effected in the present instance during theadvance of the head along the ways 11 and by the tips of a plurality ofteeth 28 comprising the comers of indexable wafers 29 secured by screwactuated clamps 31 in seats formed in and angularly spaced around theends of bars 32 (FIGS. 3 and 5). Each of these bars is secured by screws33 in slot 34 (FIGS. 4 and 5) extending along the outer end portion ofthe spindle which is formed by a sleeve 35 constituting the cutter bodyor outer end portion of the spindle 17. Herein, the tapered inner endportion 36 of this body is seated in a complemental taper in the spindleend, coupled to the latter by a key 37 and held by screws 38 havingheads disposed in recesses 39 angularly spaced around the body. Thispermits convenient removal of the cutter part of the spindle.

With the boring cutter constructed and mounted as above described, ahole 24 will be bored in the fixtured workpiece by the teeth 28 during arapid advance followed by feeding of the head 10 and spindle from theposition shown in full in FIG. 1 to that shown in phantom, the boringteeth then being disposed beyond the outward end of the hole as shown inFIG. 5. Instead of rapidly retracing the tool out of the work as iscustomary, the head may be retracted after the boring at a rate slowenough to enable another tooth 41 on the spindle to enlarge the hole asmall amount and leave the latter with a fine finish of extremelyprecise" size. Such finish boring is effected by the tip 42 of the tooth41 which projects radially and outwardly from the cutter body 35 andangularly spaced from the teeth 28. The finishing tooth is mounted forradial adjustment relative to the body between an inactive innerposition (FIG. 2) of shorter radius than the teeth 28 and an outerposition (FIG. 5) of a radius slightly greater by an amount equal to thedesired depth of the finishing cut to be taken during the retraction ofthe cutter out of the work from the position shown in phantom in FIG. 1and in full in FIG. 5. The depth of such finishing cut is indicated at fon an enlarged scale in FIG.

FINISH TOOTH MOUNTING AND ADJUSTMENT Herein the finishing tooth 42 isthe outwardly exposed comer of a wafer of suitable cutting materialdisposed in a seat 44 (FIGS. 4 and 5) in the free end portion of anelongated cantilever 45 and secured therein by a clamp 46 actuated by ascrew 47. In the form shown in FIGS. 1 to 5, the cantilever is astraight and relatively thick bar of resilient steel disposed andfitting closely in an outwardly opening slot 40 formed in the peripheryof the cutter body 35 and extending to the free end thereof generallyparallel to the spindle axis. At its inner end, the bar is anchored tothe body at the bottom of the slot by screws 48 spaced along the bar.The unsupported end portion is thus free to bend outwardly in a radialplane and thus move the tooth 41 outwardly from the inner or inactiveposition shown in FIG. 2 to the outer or active position (FIG. 5) inwhich the tooth tip 42 is disposed at a radius slightly greater than theradii of the semifinishing teeth 28. Owing to its substantial thicknessand composition, the bar is extremely stiff and requires the applicationof substantial outward pressure at its free end to bend the bar and setthe tooth 42 outwardly. Because of this, the bar providescorrespondingly increased rigidity in the support of the cutting tooth.The cantilever is stressed to swing inwardly to the FIG. 2 position whenthe outward bending pressure is relieved. By virtue of the close fittingof the cantilever bar between the side walls 40a (See FIG. 7) of theslot 40, it is held securely against lateral vibration during cuttingaction by the tooth 41 in all of its radial positions.

Outward bending of the cantilever and corresponding outward radialshifting of the tooth 41 is effected by an elongated wedge 50 which isdisposed within the tubular spindle and cutter body 35 and guidedthereby endwise forth and back along the spindle axis. Flat surfaces 51and 52 (FIGS. 5 and 6) of substantial length and width on opposite sidesof the wedge are disposed approximately perpendicular to the plane ofswinging of the cantilever 45 and converge outwardly and toward the endof the cutter at a very small angle, for example, three degrees in thepresent instance. The wedge comprises the outer end portion of a rod 53whose inner end portion is guided along the axial bore 59 of the spindleand urged inwardly by a spring 54 coiled around the inner end portion ofthe rod and acting in compression between axially spaced shoulders 55and 56 on the body and the rod to urge the latter continuously towardthe retracted position shown in FIG. 2. This position is limited by astop 57 on the inner end of the plug 58 threaded into the tapered shank36 of the cutter body. This arrangement enables the outer portion 35 ofthe spindle 17, including the shank, the cutter teeth 28, 41, and thewedge 50 to constitute a self-contained cutter unit which may be removedand replaced through the medium of the screws 38.

The surface 51 of the wedge on the side opposite the cantilever 45parallels the spindle axis as shown in FIG. 5 and is slidable along thebacked rigidlyby the inner flat surface of a bar 63 disposed in a groove62. (FIG. 7) extending along the inner face of the bar which is disposedin the transaxial plane of the cantilever and held seated in the bore 59by screws 64 as shown in FIGS. 5 and 7. To provide a similarly largebearing area on the opposite side of the wedge, a follower bar 68 isdisposed in and guided for bodily radial movement by the parallel sides69 (FIG. 7) and ends 70 of a groove 67 on the side of the bore 59opposite the backing bar 63 and extending along the outer free endportion of the cantilever. Herein, the outer end 70 is on a cap 71secured by screws to the end of the cutter body 35. The bar 68, which isurged inwardly toward the wedge by compression springs 72 (FIG. 5),bears continuously and midway between its ends against the end of ascrew 73 threaded radially into the free end portion of the cantilever45 and projecting through a radial hole 74 in the body 35 (FIG. 7). Thebar 68 and the screw 73 constitute a follower for the wedge surface 52and coact with the latter in converting and transmitting the axial forceapplied to the rod and exerting the greatly magnified resultant force onthe free end of the cantilever to bend the latter outwardly.

To effect outward bending of the extremely stiff cantilever abovedescribed, the radial force derived through the wedge action must be ofsubstantial magnitude. It is desirable therefore not only to employ awedge having a small taper and large bearing areas as determined by thelength and width of the surfaces 51, 52 but also to minimize the slidingfriction between the wedge and its backing 63 and its follower 68. Allof this is accomplished in the present instance by interposingantifriction elements of proper area and construction between theopposed wedge and backing and follower surfaces. Herein, these elementscomprise rows substantially equal in length and width to the wedgesurfaces of small diameter rollers 60 and 65 or needle bearings disposedin spaced parallel slots 60a in plastic retainer bars 61 and 66 andjournaled at opposite ends in the ends of the slots. As shown in FIG. 6,the rollers are larger in diameter than the thickness of the retainerplates. The roller units need not be confined endwise and may shift backand forth between the positions shown in FIGS. 2 and 5 relative to walls75 at the free end of the wedge. The springs 72 above described serve tohold the follower bar 68 against the row of bearings 65 and maintain theassembled relation of the follower, the bearings, and the wedge wheneverit becomes desirable to remove or replace the cantilever.

The use of the follower bar 68 and the transmission of its bodily motionoutwardly to the cantilever 45 by the screw 73 extending through a hole74 in the cutter body 35 is advantageous in facilitating manualadjustment of the cutter tooth 41 independently of the automaticmechanism about to be described. Thus, with the screw threaded into aradially disposed hole 74a in the cantilever with the socket head at itsexposed outer end, the screw is accessible from exterior of the spindle35 for convenient rough or setup adjustments of the radial position ofthe tooth 41.

Also, by fitting an O-type seal ring 730 between an external groove inthe screw 73 and the internal wall of the hole 74 in the spindle sleeve35, the latter is sealed against the ingress of coolant thus preventingforeign matter from coming onto the needle bearings and wedge surfaces.

ACTUATION OF ADJUSTING ROD Power for advancing the wedge 50 from thenormally retracted position shown in FIG. 2 is derived from a suitableactuator 76 mounted on the head [0 beyond the upper end of the sleeve 14and connected to the wedge through a rod 77 extending along the spindleaxis and abutting the inner end 78 of the wedge rod 53. While wedgesurfaces may taper inwardly from the end of the spindle and the wedgepulled inwardly to effect the tooth set-out, the outward taper abovedescribed requires that the wedge be pushed outwardly to bend thecantilever and be pulled inwardly, herein by the spring 54, to allow thecantilever to retract the tooth 41.

In the form shown, the actuator 76 comprises a piston 79 rigidlyconnected to the upper end of the push rod 77 and slidable in a cylinder81 bolted to the top 82 of the head 10, the advanced and retractedpositions of the piston being shown in FIGS. 2 and 8. The push rod isdivided into lower, intermediate and upper parts 83, 84, 85, the latterbeing the rod of the piston 79 which is connected to a sleeve 86threaded onto the upper end of the rod 84. To permit the wedge to turnwith the spindle without turning of the intermediate part 84, the latteris coupled through a bearing assembly 87 to the rod 83 whose reducedlowered end 88 is telescoped into the plug 58 into abutment with the end78 of the cutter adjusting rod 53. The coupling disposed above the drivepulley 22 comprises antifriction bearings 89 retained in inner and outerrace ways secured respectively to the upper end of the rod 83 and aninverted cup 91 fixed to the lower end of the push rod 84. Below thebearing assembly, the rod 83 is guided in a bushing 95 within the pulley22 and slides along a key 96 carried by this bushing.

WEDGE POSITIONING STOPS AND STEP ADJUSTMENT THEREOF The advance of thepiston rod and therefore the set-out of the tooth 41 through the wedgeand cantilever as above described is gaged with extreme precision byabutment of the "van rm-m lower end 92 of the sleeve 86 on the pistonrod with a stop 93 fixed on the boring head but adjustable along thespindle axis to permit the expanded position of the tooth tip 42 to bevaried. Preferably, the stop 93 comprises the upper end of a tubularscrew 94 telescoped around the rod 84 and extending through and guidedfor endwise movement in a flanged bushing 97 secured to a partition 98within the boring head 10. A key 99 on the screw body 100 projects intoan elongated slot 101 extending along the bushing, the screw is thusheld against turning but is adjustable endwise along the bushing. A key102 and slot 103 spline couples the screw to the rod 84.

Axial adjustment of the screw 94 and therefore the stop 93 is effectedby turning a nut 104 threaded onto the upper end of the screw and heldagainst a bearing ring 105 on the upper end of the bushing 97. Backlashin the screw coupling is thus taken up by springs 106 acting incompression between the lower end of the bushing and a flange 107 of thescrew body.

It will be apparent that when the piston 79 of the actuator 76 is raisedto an upper limit position shown in phantom in FIG. 2, the abutment isseparated from the stop 93 which is then free to be raised or lowered asdesired. In the raising of the piston 79, the push rod 77 and the wedgethereon are retracted upwardly by the spring 54 thus allowing thecantilever to bend inwardly and retract the tooth 41 away from boringposition and to a position determined by the stop 57 on the boringspindle. Such changing of the position of the adjustable stop 93 ispreferably effected by an actuator which is reversible, operablestep-by-step, and easily controllable, preferably by simple electriccircuitry, so that the extent of the tooth setout in successive boringcycles may be gaged accurately and in advance of the time when theboring by the tooth 41 is to occur. To accomplish this with minimum costof equipment, the invention utilizes an electric stepping motor 108(FIGS. 8 and 9) of conventional construction but one which is reversibleand controllable through simple circuitry correlated with the cycles ofthe boring machine above described. The casing of the motor 108 isbolted to the partition 98 and the upright motor shaft 109 carries atoothed pulley 110 meshing with the teeth of an endless timing belt 11 1extending around and meshing with complemental teeth on a pulley 112telescoped around and secured by screws 113 to the nut 104.

Motors of the stepping type have a permanent magnet rotor 115 (FIG. 9)which is indexed in fixed steps and to a multiplicity, for example 200per revolution, of stable positions by successive direct current pulses.Thus, by closure of a control switch 116 acting through conventionalcircuitry, the windings of the motor are excited sequentially to turnthe rotor through any desired number of its steps as determined by acontroller mounted in a panel 120 and including components such as aresettable pulse counter, pulse gate, oscillator and translatorinterconnected in a standard NEMA logic circuit. Suitable for thepresent purpose are the components and a stepping motor, identified asS8250, sold by the Superior Electric Company. This motor is reversible,the direction of its stepping being determined by the selectiveactuation of a switch 114 (FIG. 9) by turning of a knob 136. For theboring operation above described, the counter of themotor controller isset to cause turning of the motor shaft through a plurality, forexample, five steps or one-fiftieth of a revolution. Such turning astransmitted through the timing belt 111, the nut and screw, the wedge 50and the cantilever 45 produces a radial adjustment of the tooth 41 ofabout 0.000] of an inch.

CONTROL CIRCUITRY AND OPERATION In the course of repeated cyclesperformed on successive workpieces by the rough and finish boring teeth29 and 41 mounted and actuated as above described, the tooth tip 42wears down resulting in finished bores of smaller sizes which may bedetected with great precision through the use of conventional inspectiongages. The undersize condition of a work bore may be indicated on asuitable gage after which the switch 116 may be closed manually by theinspecting operator. Such closure will, when the tool head 10 is fullyretracted, as evidenced by closure of the limit switch LSr by the cam146, be effective to pulse the motor 108 and advance the stop 93 onestep and in a direction determined by which of the selector switchcontacts 114a or 114b is closed. If the switch is set for outwardadjustment of the tooth 41, the latter will be set out of thepredetermined increment f (FIG. 5) or 0.000l of an inch in thisinstance. In the case of an inspection assembly built into an automatictransfer line-up, the switch 116 may be closed automatically in responseto the detection of the undersize condition, this signal being retainedand used in the next cycle of the boring machine to adjust the stop 93downwardly and cause the finishing tooth 41 to be set outwardly as abovedescribed.

The boring machine constructed as above described is intended duringeach automatic cycle comprising advance of the head 10 and return to theretracted position shown in FIG. 1 to enlarge a hole 25 in the fixturedworkpiece 26 first to a diameter 11 (FIG. 5) by the action of the teeth28 while the tooth 41 is held retracted (FIG. 2) and then, afterautomatic setting of the tooth 41 outwardly to its active position (FIG.5), to further enlarge the hole to the diameter d as the head isretracted from its most advanced position. Typical and conventionalelectric and hydraulic circuitry for activating the head and push rodactuators 13 and 76 for executing such a cycle is shown in FIG. 9.

After the completion of one cycle of the boring machine above described,the tool head will be retracted and the piston of the actuator 76 willbe raised thus raising the push rod to separate the abutment 92 from theadjustable stop 93 (FIG. 2) and allow the wedge 50 to be raised by thespring 54 and the cantilever to bend inwardly thus retracting the tooth41 to active position. At this time, the various parts will bepositioned as shown in full in FIG. 9.

An automatic cycle is initiated in response to closure of a startingswitch 117 which results in energization of a solenoid which shifts avalve upwardly and to admit high pressure fluid from a motor driven pump142 to a line 143 leading to a direction control valve 119. The switch117 also completes a circuit for energizing the solenoid 118 of thisvalve thus admitting pressure fluid to the head end of the cylinder 13while connecting the rod end thereof to a drain line 144 through a thenopen valve 122. Rapid downward advance of the head 10 is thus initiated.As the teeth 28 approach the hole 25 to be bored as shown in phantom inFIG. 9, the cam 146 on the head 10 closes the switch LSal thusenergizing the solenoid 121 of the valve 122 to interposing arestriction 123 in the path of fluid flow out of the rod end of thecylinder 13. The head advance then continues at a slower rate duringfeeding of the teeth 28 through the work to semifinish bore the hole 25.

After the teeth 28 pass the lower end of the work hole as shown indotted outline in FIG. 9, the cam 146 closes a limit switch LSf toenergize the solenoid 124 so as to reverse the valve 119 and direct highpressure fluid to the rod end of the cylinder 13 and release fluid fromthe head end through the restriction 123. Upward retraction of the headis thus initiated at a slow rate for finishing boring by the tooth 41.At the same time and, before the finishing tooth 41 reaches the lowerend of the semifinished bore, closure of LS] by the earn 146 completes acircuit for energizing a solenoid 126 which shifts a valve 127 to directhigh pressure fluid to the head end of the cylinder 81 and advance thepiston 79 and the push rod 77 until the abutment 92 comes against thestop 93. In such advance, the wedge 50 cams the cantilever 45 andthetooth 41 outwardly to a position determined by the prevailingposition of the stop 93. The tip 42 of the tooth is then for enlargingthe hole to the diameter d which occurs as the retraction of the head 10and spindle continue at the feed rate established by the restriction123.

When the tooth 41 passes out of the upper end of the work bore andreaches the position shown in phantom in FIG. 9, a switch LSa2 is closedby the cam 146, thus energizing a solenoid 128 to open the valve 122 andpermit the flow of high pressure fluid to the rod end of the cylinder 13to continue at an increased rate for returning the head rapidly to thestarting position. On reaching the position shown in FIGS. 1 and 9, thecam 146 on the head closes a switch LSrl energizing a solenoid 147 bywhich the valve 141 is shifted back to the stop position shown in FIG.9.

Closure of LSa2 during the rapid return of the head also completes acircuit for energizing a solenoid 129 for reversing the valve 127 todirect high pressure to the rod end of the cylinder 81 and thus retractthe push rod and the wedge 50 allow the tooth 41 to be retractedinwardly to the inactive position (FIG. 1) determined by the stop 56.Retraction of the push rod also separates its abutment 92 from the stop93 so that the latter is free for readjustment by the step motor 108 ifsuch readjustment is needed to compensate for wear at the tooth tip 42.

As an incident to such retraction, a cam 130 (FIGS. 2, 8 and 9) on thepush rod portion 86 closes a limit switch 131 coacting with the thenclosed limit switch LSr to condition a circuit 132 to energize a relay133 if the switch 116 is then closed. Energization of this relay closesa sealing switch 134 so that the relay remains energized long enough forthe associated switches of the logic circuitry to initiate a pulsingcycle of the stepping motor 108. Thus if, at the time the head 10 andthe push rod 77 are retracted, the switch 116 is closed as evidence ofthe need for outward adjustment of the tooth 41, the step motor 108 willbe energized and its rotor turned through the predetermined angle thusturning the nut 104 and lowering the stop 93 correspondingly. In thisnew position, the stop will, in the next boring cycle as above describedand during the advance of the push rod after semifinishing of the boreby the teeth 28, cause the wedge to set the tooth 41 outwardly anadditional increment, for example 0.0001 of an inch. If such a singlestep of adjustment is insufiicient to correct for the undersize of theholes being bored, the switch 116 is actuated again and used in one ormore ensuing boring cycles to further adjust the stop 93 and cause thetooth 41 to be set out in similar increments at the ends of the headadvance in each of such cycles.

By virtue of its reversible character, the same electric step motor 108may, though the medium of the selector switch 114, be used incombination with a switch 137 to run the step motor under manual controlin either direction thus facilitating the initial adjustment of the stop93 or resetting of the same after replacement of a worn tooth 41 on thespindle. This may be accomplished by first setting the knob 136according to the desired direction of the stepping and the closing theswitch 137 until the stop has reached the desired position.

During normal cycling of the machine for boring successive workpieces,the switch 114b will be left closed so that the step motor will beconditioned for lowering the stop 93 each time it is energized byclosure of the switch 137. When it becomes desirable to replace thecutter head 35 having new cutting teeth thereon, the stop 93 will bereset to a higher position. This is accomplished by turning the knob 136to close the switch 114a so that, upon closure of the switch 137, themotor 108 will run in a direction to raise the stop. Such reverseoperation of the step motor may be effected whenever the stop is loweredin the course of successive boring cycles, far enough to result in thefinishing of the bore to a diameter larger than that desired.

MODIFIED CANTILEVER TOOTH MOUNTING To adopt the adjustable toothmounting for use in boring holes of diameters smaller than that of thespindle and cutter body 35, the free end portion of the cantilever ismodified as shown in FIGS. 10 to 12 and extended beyond the end of thebody and inwardly so that the tip 42 of the the tooth 41 may be disposedat a desired short radius. The parts common to the structure firstdescribed bear the same reference numerals.

For such modification, the cantilever 45 preferably takes the form of afork of right angular U-shape having parallel legs 151 and 152straddling the free end of the cutter head 35 and a projection 153 rightwith and extending outwardly from the center of the crosspiece 154 ofthe fork and along the rotational axis of the spindle. The tooth 41 foreffecting the finish boring is secured to the projection in the mannerabove described and its radial position according to the size of thehole to be bored, is determined by the diameter of the projection. Tocover the end of the cutter body and exclude foreign matter from thewedge and bearing, the crosspiece preferably comprises a cup telescopedloosely over the free end of the body 35.

The leg 151 of the fork is constructed, mounted and actuated the same asthe straight bar cantilever above described. At its inner end, it isanchored to the cutter body 35 by screws 48 and threaded to receive thescrew 73 bearing against the follower bar 68. In a similar way, screws161 anchor the inner end of the other fork leg 152 to the body 35 on theside thereof opposite the leg 151. Thus, both legs 151, 152 bend backand forth laterally and in unison with changes in the axial position ofthe wedge 50, the radial position of the tooth tip 42 being changedcorrespondingly substantially the same as in the structure firstdescribed. Preferably, the projection 153 is a separately formed barsmaller in diameter than the holes to be bored by the tooth 41 andhaving at the inner end a flange 155 clamped by screws 156 to thecrosspiece 154 and held centered relative to the spindle axis by a closetelescoping of a pilot 157 thereon fitting into a correspondingly shapedrecess 158 in the outer face of the crosspiece.

In spite of the elongation of the cantilever in order to dispose thetooth tip 42 at a short radius for boring small holes, provision is madefor adjustment of the tip substantially in a true radial direction. Toaccomplish this, the legs 151 and 152 are constructed to induce bendingthereof along parallel lines extending transversely of the legs close tothe points of anchorage defined by the screws 48 and 161. In a similarway, the legs are weakened and bending thereof is facilitated alongtransversely extending lines spaced outwardly a short distance beyondthe follower screw 73.

The above described weakening of the cantilever legs is achieved byforming relatively shallow and rounded bottom grooves 162, 163 acrossthe inner sides of the legs along the lines above described. With thelegs constructed and mounted as above described, the parts thereofbetween the grooves 161 and 162 constitute in effect opposite sides of aparallelogram whose outer end formed by the crosspiece 154 is rigid withand supports the cutter tooth 41 for movement substantially in theradial plane. The tooth tip 42 is thus maintained in essentially thesame relation to the spindle axis in all of the positions of radialadjustments.

WEDGE MODIFICATION FOR MULTIPLE TOOTH CU'I'IERS The cantilever toothmounting and wedge adjusting action above described may be employed inboring cutters where it is desirable to employ a plurality of thefinishing teeth 41 and thus reduce the loading on the individual teethor increase the production capacity of the boring machine. Modificationof the structure above described for achieving this objective isillustrated in FIGS. 13 to 16 in which three finishing blades 41,41a,'4lb are equidistantly spaced around the cutter body, mounted andsupported on the free ends of straight bar cantilevers 45a, 45b and 45cof the construction first described and set out simultaneously and inequal increments in the advance of the push rod 53 in the boring cyclesexecuted in the manner above described.

The cantilevers disposed in grooves equally spaced around the body aresimilarly anchored at their inner ends and connected near the free endsby screws 73a, 73b and 730 to follower bars 68a, 68b and 680. The latterare mounted in grooves in the cutter body for bodily radial movementand, along their inner edges, bear against rows of needle bearings 65a,65b and 65c, held in suitable retainers and bearing on their inner sidesagainst surfaces 52a, 52b and 52c of a wedge 50 advanced axially andretracted in the same manner described above. As before, the wedgesurfaces are inclined at the same small angle relative to the spindleaxis and are spaced equidistantly around the wedge.

Along the side of the wedge opposite each of the inclined surfaces is aflat surface 51a, 51b and 51c paralleling the axis of the spindle andcontacting a row of needle bearings 60a, 60b and 60c which are backed bybars 63a, 63b and 63c mounted on the inner wall of the cutter body, thesame as in the single tooth finishing tool first described. Thus, thewedge is of hexagonal cross section with the inclined surfaces 52 spacedequidistantly around the wedge and alternating with the surfaces 51backed by the bars 63a, 63b and 630 similarly spaced around the interiorof the cutter body 35.

With the arrangement above described, it will be apparent that the wedge50 is utilized to control accurately the radial positioning of the tips42 of a plurality of angularly spaced teeth carried by a single cutterbody. The loading on each tooth may thus be decreased correspondingly inthe removal of metal to enlarge a work bore to a desired diameter.

We claim:

1. The combination of, a tool head, a rotary tubular spindle joumaled insaid head and projecting cantilever fashion therefrom, an elongated andresilient cantilever extending along the end portion of said spindle andanchored to the spindle at a point spaced from the free end thereofwhereby to provide for outward and inward radial bending of the free endportion of the lever, a cutting tooth fixed to the free end of saidcantilever so as to be adjustable outwardly to an active cuttingposition by outward bending of said cantilever, a wedge of smallincluded angle disposed within and movable axially back and forth alongsaid spindle and said cantilever, a backing surface rigid with saidspindle on the side thereof opposite said cantilever, first and secondrows of antifriction bearing elements disposed along opposite sides ofsaid wedge and between such sides and said cantilever and said backingsurface respectively, a rigid follower extending along and disposedwithin said spindle between said cantilever and the first row of saidelements, means on the spindle holding said follower against movementaxially of the spindle while supporting the follower for radial movementin response to axial movements of said wedge in opposite directions, andmeans providing between the free end portion of said cantilever and saidfollower a rigid connection for transmitting the radial movements of thefollower to said cantilever to effect positive outward bending thereofand corresponding outward adjustment of said tooth in response to axialmovement of said wedge in one direction while permitting reverse bendingand inward retraction of the tooth with opposite axial movement of thewedge.

2. The combination defined in claim 1 in which the opposed surfacesengaged by said bearing elements are flat and each row of said elementscomprises a plurality of parallel rollers spaced along said spindle.

3. The combination defined in claim 2 including retainers holding therollers of each of said rows in spaced parallel relation.

4. The combination defined in claim l in which said follower is a rigidbar mounted for bodily radial floating relative to the spindle.

5. The combination defined in claim 1 in which the opposite sides ofsaid wedge that engage said bearing elements converge toward each otherand toward the spindle end whereby the cantilever is bent outwardly inresponse to endwise pushing of the wedge relative to the spindle.

6. The combination defined in claim 1 in which said cantilever andfollower are rigid and said last mentioned means is a radially extendingmember secured at one end in one of the bars and, at its other end,abutting the other bar.

7. The combination defined in claim I in which said rigid connectingmeans extends radially between a point intermediate the ends of saidfollower and a point spaced along the cantilever away from the anchoredend thereof.

8. The combination of, a tool head, a rotary tubular spindle journaledin said head and projecting cantilever fashion therefrom, an elongatedand resilient cantilever extending along the end portion of said spindleand anchored to the spindle at a point spaced from the free end thereofwhereby to provide for outward and inward radial bending of the free endportion of the lever, a cutting tooth fixed to the free end of saidcantilever so as to be adjustable outwardly to an active cuttingposition by outward bending of said cantilever, an elongated wedge ofsmall included angle and having opposite flat side surfaces disposedwithin and movable axially back and forth along said spindle and saidcantilever, an elongated backing surface on said spindle correspondingin length to the Wedge and rigidly backing the same on the side thereof0pposite said cantilever, an elongated and rigid follower bar extendingalong and disposed within said spindle between said cantilever and theopposite side of said wedge, means on the spindle holding said baragainst movement axially of the spindle while supporting the bar forradial movement in response to axial movements of said wedge in oppositedirections, and a member providing a rigid connection between saidcantilever and the intermediate portion of said bar whereby to effectpositive outward bending of the cantilever in response to axial movementof said wedge in one direction while permitting reverse bending withopposite axial movement of the wedge.

9. The combination defined in claim 8 including parallel roller bearingsspaced apart along said wedge and arranged in rows substantially as longas said follower bar, one row being disposed between and bearing againstsaid backing surface and the opposed surface of the wedge and the otherrow being disposed between the other wedge surface and said followerbar.

10. The combination defined in claim 8 in which said cantilever is anelongated bar and the member is a screw threaded at one end into one ofsaid bars transversely thereof.

ll. The combination defined in claim 10 in which the outer end of saidscrew is exposed and adapted for engagement with a tool for turning thescrew to'vary the spacing of the cantilever from said follower bar.

12. The combination defined in claim 8 in which said cantilever isdisposed in a radially opening slot in said spindle having parallel sidewalls engaging opposite longitudinal sides of the cantilever toaccurately guide the radial bending thereof and hold the cantileveragainst vibration during cutting engagement of said tooth with aworkpiece in all of the adjusted positions of said tooth.

13. The combination as defined in claim 8 in which said member extendsradially through a hole in said spindle including means providing afluid tight seal between the member and spindle so as to prevent theentry of foreign matter to said follower bar and wedge surfaces whilepermitting free radial movement of the member.

14. The combination defined in claim 1 in which said cantilevercomprises a fork of generally U-shape having laterally spaced legsstraddling the free end of said spindle and anchored at their ends toopposite sides of said spindle, a crosspiece disposed beyond andextending across said spindle end, and a member rigid with andprojecting from the center of said crosspiece and supporting saidcutting tooth in boring position at a point spaced from the spindle end,said connecting means joining one of said legs with said follower.

15. The combination defined in claim 14 in which the leg of the U on theside of said spindle opposite said follower is disconnected from thefollower and free to swing laterally back and forth with the first leg.

16. The combination defined in claim 15 in which said crosspiece of saidcantilever comprises a disk disposed adjacent and covering the free endof said spindle.

17. The combination defined in claim 1 in which said cantilever includesa rigid extension projecting along said spindle beyond the end thereofand then inwardly toward the spindle axis, and means on the free end ofthe cantilever beyond the spindle end supporting said tooth with the tipthereof disposed at a radius shorter than the radius of the spindle.

18. The combination defined by claim 17 in which the free end portion ofsaid cantilever is a bar projecting along the axis of the spindle beyondthe free end of the latter.

19. The combination defined in claim 8 in which the assembly comprisingsaid cantilever, said wedge and backing surfaces, said follower and saidtooth are disposed in a common transaxial plane, and including one ormore similarly constructed assemblies of a cantilever, cutting tooth,wedge and backing surfaces and follower similarly mounted in a commontransaxial plane, said assembly planes being equidistantly spaced aroundsaid spindle axis whereby to balance the laterally directed forcesholding the several cutting teeth during the boring of a work hole.

20. The combination of, a tool head, a tubular spindle journaled by saidhead and projecting therefrom, a cutter tooth mounted on the free endportion of said spindle for adjustment radially of the spindle betweenan inner inactive position and an outer cutting position, an operatingrod disposed within said spindle and movable along the axis thereof, areversible power actuator mounted on said head and operable to move saidrod in first and second directions axially of the spindle, means withinsaid spindle coupling said rod to said tooth and operable to set thetooth outwardly during movement of the rod in said first direction andto cause retraction of the tooth inwardly as the rod is moved in saidsecond direction, a tubular screw element surrounding said rod, a nutelement threaded onto the screw element, means on said head supportingone of said elements in an axially fixed position and for rotation aboutthe'spindle axis, means on said head supporting the other of saidelements for movement along said axis while holding such element againstturning, a stop movable with said other element in response to turningof the rotatable element, an abutment movable with said rod andengageable with said stop to limit the advance of the rod in said firstdirection by said power actuator, and means on said head for turningsaid rotatable element selectively to thereby adjust the position ofsaid stop.

21. The combination defined in claim 20 in which said stop is fixed toone end of one of said elements and said abutment is fixed to said rod.

22. The combination defined in claim 21 in which said other element isthe screw and the rotatable element is a nut threaded onto such screw,

23. The combination defined in claim 20 in which said turning meanscomprises an electric motor of the stepping type having a rotor turnedangularly through a predetermined angle each time the motor isenergized.

24. The combination defined in claim 23 including means coupling saidstepping motor to said rotatable element and selectively operable meansfor pulsing said motor to turn such element in steps of predeterminedarcuate length and thereby determine the increments of advance of saidstop and therefore of set-out of said cutting tooth.

25. The combination as defined in claim 23 in which said stepping motorincludes windings selectively energizable to cause rotation in oppositedirections and adjustment of said stop in a direction corresponding tothe selected direction of rotation.

26. The combination as defined in claim 20 for enlarging a hole in aworkpiece including means operating in a continuous cycle to advance andretract said head toward and away from a workpiece to advance andretract said spindle and cutting tooth into and through said work hole,and means operating in response to movement of said head to maintainsaid actuator inactive and said tooth retracted inwardly during theadvance of the head and movement of the tooth through and beyond thework hole, to activate the actuator before the tooth reaches said holeduring retraction of the head and, during such retraction of saidspindle and tooth through said hole, to maintain the actuator active andthe tooth in said active position.

27. The combination as defined in claim 26 including power actuatedmeans adapted when activated to adjust said stop relative to said headfor setting said tooth outwardly a predetermined increment when saidactuator is again activated, a member movable to a set positionindicating the need for outward adjustment of said tooth, and meansresponsive to the location of said member in said set position toactivate said power actuated means while said abutment is out ofengagement with said stop.

1. The combination of, a tool head, a rotary tubular spindle journaledin said head and projecting cantilever fashion therefrom, an elongatedand resilient cantilever extending along the end portion of said spindleand anchored to the spindle at a point spaced from the free end thereofwhereby to provide for outward and inward radial bending of the free endportion of the lever, a cutting tooth fixed to the free end of saidcantilever so as to be adjustable outwardly to an active cuttingposition by outward bending of said cantilever, a wedge of smallincluded angle disposed within and movable axially back and forth alongsaid spindle and said cantilever, a backing surface rigid with saidspindle on the side thereof opposite said cantilever, first and secondrows of antifriction bearing elements disposed along opposite sides ofsaid wedge and between such sides and said cantilever and said backingsurface respectively, a rigid follower extending along and disposedwithin said spindle between said cantilever and the first row of saidelements, means on the spindle holding said follower against movementaxially of the spindle while supporting the follower for radial movementin response to axial movements of said wedge in opposite directions, andmeans providing between the free end portion of said cantilever and saidfollower a rigid connection for transmitting the radial movements of thefollower to said cantilever to effect positive outward bending thereofand corresponding outward adjustment of said tooth in response to axialmovement of said wedge in one direction while permitting reverse bendingand inward retraction of the tooth with opposite axial movement of thewedge.
 2. The combination defined in claim 1 in which the opposedsurfaces engaged by said bearing elements are flat and each row of saidelements comprises a plurality of parallel rollers spaced along saidspindle.
 3. The combination defined in claim 2 including retainersholding the rollers of each of said rows in spaced parallel relation. 4.The combination defined in claim 1 in which said follower is a rigid barmounted for bodily radial floating relative to the spindle.
 5. Thecombination defined in claim 1 in which the opposite sides of said wedgethat engage said bearing elements converge toward each other and towardthe spindle end whereby the cantilever is bent outwardly in response toendwise pushing of the wedge relative to the spindle.
 6. The combinationdefined in claim 1 in which said cantilever and follower are rigid barsand said last mentioned means is a radially extending member secured atone end in one of the bars and, at its other end, abutting the otherbar.
 7. The combination defined in claim 1 in which said rigidconnecting means extends radially between a point intermediate the endsof said follower and a point spaced along the cantilever away from theanchored end thereof.
 8. The combination of, a tool head, a rotarytubular spindle journaled in said head and projecting cantilever fashiontherefrom, an elongated and resilient cantilever extending along the endportion of said spindle and anchored to the spindle at a point spacedfrom the free end thereof whereby to provide for outward and inwardradial bending of the free end portion of the lever, a cutting toothfixed to the free end of said cantilever so as to be adjustableoutwardly to an active cutting position by outward bending of saidcantilever, an elongated wedge of small included angle and havingopposite flat side surfaces disposed within and movable axially back andforth along said spindle and said cantilever, an elongated backingsurface on said spindle corresponding in length to the wedge and rigidlybaCking the same on the side thereof opposite said cantilever, anelongated and rigid follower bar extending along and disposed withinsaid spindle between said cantilever and the opposite side of saidwedge, means on the spindle holding said bar against movement axially ofthe spindle while supporting the bar for radial movement in response toaxial movements of said wedge in opposite directions, and a memberproviding a rigid connection between said cantilever and theintermediate portion of said bar whereby to effect positive outwardbending of the cantilever in response to axial movement of said wedge inone direction while permitting reverse bending with opposite axialmovement of the wedge.
 9. The combination defined in claim 8 includingparallel roller bearings spaced apart along said wedge and arranged inrows substantially as long as said follower bar, one row being disposedbetween and bearing against said backing surface and the opposed surfaceof the wedge and the other row being disposed between the other wedgesurface and said follower bar.
 10. The combination defined in claim 8 inwhich said cantilever is an elongated bar and the member is a screwthreaded at one end into one of said bars transversely thereof.
 11. Thecombination defined in claim 10 in which the outer end of said screw isexposed and adapted for engagement with a tool for turning the screw tovary the spacing of the cantilever from said follower bar.
 12. Thecombination defined in claim 8 in which said cantilever is disposed in aradially opening slot in said spindle having parallel side wallsengaging opposite longitudinal sides of the cantilever to accuratelyguide the radial bending thereof and hold the cantilever againstvibration during cutting engagement of said tooth with a workpiece inall of the adjusted positions of said tooth.
 13. The combination asdefined in claim 8 in which said member extends radially through a holein said spindle including means providing a fluid tight seal between themember and spindle so as to prevent the entry of foreign matter to saidfollower bar and wedge surfaces while permitting free radial movement ofthe member.
 14. The combination defined in claim 1 in which saidcantilever comprises a fork of generally U-shape having laterally spacedlegs straddling the free end of said spindle and anchored at their endsto opposite sides of said spindle, a crosspiece disposed beyond andextending across said spindle end, and a member rigid with andprojecting from the center of said crosspiece and supporting saidcutting tooth in boring position at a point spaced from the spindle end,said connecting means joining one of said legs with said follower. 15.The combination defined in claim 14 in which the leg of the U on theside of said spindle opposite said follower is disconnected from thefollower and free to swing laterally back and forth with the first leg.16. The combination defined in claim 15 in which said crosspiece of saidcantilever comprises a disk disposed adjacent and covering the free endof said spindle.
 17. The combination defined in claim 1 in which saidcantilever includes a rigid extension projecting along said spindlebeyond the end thereof and then inwardly toward the spindle axis, andmeans on the free end of the cantilever beyond the spindle endsupporting said tooth with the tip thereof disposed at a radius shorterthan the radius of the spindle.
 18. The combination defined by claim 17in which the free end portion of said cantilever is a bar projectingalong the axis of the spindle beyond the free end of the latter.
 19. Thecombination defined in claim 8 in which the assembly comprising saidcantilever, said wedge and backing surfaces, said follower and saidtooth are disposed in a common transaxial plane, and including one ormore similarly constructed assemblies of a cantilever, cutting tooth,wedge and backing surfaces and follower similarly mounted in a commontransaxial plane, said assembly planes bEing equidistantly spaced aroundsaid spindle axis whereby to balance the laterally directed forcesholding the several cutting teeth during the boring of a work hole. 20.The combination of, a tool head, a tubular spindle journaled by saidhead and projecting therefrom, a cutter tooth mounted on the free endportion of said spindle for adjustment radially of the spindle betweenan inner inactive position and an outer cutting position, an operatingrod disposed within said spindle and movable along the axis thereof, areversible power actuator mounted on said head and operable to move saidrod in first and second directions axially of the spindle, means withinsaid spindle coupling said rod to said tooth and operable to set thetooth outwardly during movement of the rod in said first direction andto cause retraction of the tooth inwardly as the rod is moved in saidsecond direction, a tubular screw element surrounding said rod, a nutelement threaded onto the screw element, means on said head supportingone of said elements in an axially fixed position and for rotation aboutthe spindle axis, means on said head supporting the other of saidelements for movement along said axis while holding such element againstturning, a stop movable with said other element in response to turningof the rotatable element, an abutment movable with said rod andengageable with said stop to limit the advance of the rod in said firstdirection by said power actuator, and means on said head for turningsaid rotatable element selectively to thereby adjust the position ofsaid stop.
 21. The combination defined in claim 20 in which said stop isfixed to one end of one of said elements and said abutment is fixed tosaid rod.
 22. The combination defined in claim 21 in which said otherelement is the screw and the rotatable element is a nut threaded ontosuch screw.
 23. The combination defined in claim 20 in which saidturning means comprises an electric motor of the stepping type having arotor turned angularly through a predetermined angle each time the motoris energized.
 24. The combination defined in claim 23 including meanscoupling said stepping motor to said rotatable element and selectivelyoperable means for pulsing said motor to turn such element in steps ofpredetermined arcuate length and thereby determine the increments ofadvance of said stop and therefore of set-out of said cutting tooth. 25.The combination as defined in claim 23 in which said stepping motorincludes windings selectively energizable to cause rotation in oppositedirections and adjustment of said stop in a direction corresponding tothe selected direction of rotation.
 26. The combination as defined inclaim 20 for enlarging a hole in a workpiece including means operatingin a continuous cycle to advance and retract said head toward and awayfrom a workpiece to advance and retract said spindle and cutting toothinto and through said work hole, and means operating in response tomovement of said head to maintain said actuator inactive and said toothretracted inwardly during the advance of the head and movement of thetooth through and beyond the work hole, to activate the actuator beforethe tooth reaches said hole during retraction of the head and, duringsuch retraction of said spindle and tooth through said hole, to maintainthe actuator active and the tooth in said active position.
 27. Thecombination as defined in claim 26 including power actuated meansadapted when activated to adjust said stop relative to said head forsetting said tooth outwardly a predetermined increment when saidactuator is again activated, a member movable to a set positionindicating the need for outward adjustment of said tooth, and meansresponsive to the location of said member in said set position toactivate said power actuated means while said abutment is out ofengagement with said stop.